This invention relates generally to windshields to be mounted on motorcycles just forwardly of the rider by way of his protection from unfavorable weather or the reduction of drag. More specifically, the invention has to do with a motorcycle windshield apparatus including facilities for continuously varying the height of the windshield with respect to the motorcycle frame.
The adjustable height windshield apparatus of this invention is not desired to be of exclusive application to any particular type or class of motorcycle. Thus the term "motorcycle" as used herein and in the claims appended hereto should be interpreted in a broad sense, inclusive of any motor vehicle operating on two or three wheels in contact with the ground, regardless of the piston displacement of the propelling engine incorporated in the vehicle.
Some motorcycles, especially two wheeled motorcycles of relatively larger engine displacement, are furnished with a windshield in combination with a cowling or fairing for the production of a smooth outline and the reduction of drag. The windshield itself is further intended to protect the rider during inclement weather. Thus, when the weather is propitious, it is desirable that the windshield be retracted or lowered to such an extent as to permit the rider to look over the same. The windshield may be raised to above eye level when the vehicle is running through adverse weather. Moreover, desirably, the windshield should be adjustable to any desired height position between the two extreme positions, depending, for instance, upon the eye level of the driver or the scope of vision sought to be commanded.
U.S. Pat. No. 4,355,838 to Hickman represents a conventional example of adjustable windshield device. This patent teaches the attachment of a pair of elongate female members to the windshield, and of a pair of male track members to the cowling. The female members, together with the windshield thereon, slide up and down along the male track members to a desired height position. Lock screws are provided for locking the male and female members together in a selected windshield position.
An objection to this known device is that the motorcycle must be at a standstill, and possibly the operator must come off the saddle, for the height adjustment of the windshield. The adjustment itself is very troublesome and time consuming, necessitating the loosening and retightening of the lock screws. Additional objection is that the male and female members are disposed some distance displaced toward the median plane of the vehicle from the opposite side edges of the windshield. Therefore, especially when the windshield is elevated, the female members affixed to the windshield obstruct the rider's field of view, besides being objectionable from an aesthetic point of view.
A more advanced adjustable windshield apparatus is described and claimed in Japanese Laid Open Patent Application No. 60-8176. This second prior art apparatus employs a pair of toothed drive tapes of flexible material in combination with a pinion in mesh with both drive tapes. The drive tapes are both secured each at one end to the bottom end of the windshield, extend downwardly therefrom in parallel spaced relation to each other, and are bent right angularly toward each other to provide horizontal portions slidably extending along guide means on the cowling. Vertically offset from each other, the horizontal portions of the two drive tapes extend over and under, respectively, the pinion in positive engagement therewith, the pinion being rotatably mounted in a central position on the cowling.
Thus, as the pinion is revolved bidirectionally, the pair of drive tapes synchronously and longitudinally travel along the guide means, causing the windshield to travel up and down with respect to the cowling. All that is required for windshield height adjustment is to turn the pinion shaft.
Despite the simplicity of construction and the ease of manipulation, this second prior art apparatus has its own weaknesses. One of these is that the drive tapes partly overlie the windshield, and that at its central portion, presenting obstacles to the forward vision of the rider just as in the first described conventional device. Another weakness is that the drive tape and pinion arrangement serves solely to move the windshield up and down; that is, additional separate means are required for guiding the up and down motion of the windshield. As a further disadvantage, an exertion of a considerable torque is required for turning the pinion shaft and hence for longitudinally displacing the pair of drive tapes. This is because the drive tapes must slide along guideways that are each bent right angularly and, moreover, because the tapes are twisted at the right angular bends.